[msan] Enable again to get a build log, and try to play with suppressions

.circleci/config.yml

diff --git a/.circleci/config.yml b/.circleci/config.yml
index 66489e8..e5640b5 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -249,7 +249,7 @@
       - archlinux-debug-O0-py3
       - clang-O3-O0
       - clang-asan
-      #- clang-msan
+      - clang-msan
       - clang-tsan
       - clang-ubsan
       - fedora-outoftreebuild